The snow also caused some disruption at Sumburgh Airport on Monday where problems with the de-icing machine meant flights off the island were delayed for around four hours. A spokeswoman said flights were back to normal in the afternoon.

Meanwhile the Nesting and Girlsta Up-Helly-A’ was cancelled due to the bad weather. The procession, burning and squad acts were all called off on Friday evening and also the guizers’ hop the following night. The committee is due to meet to discuss the possibility of holding the event in March instead.

The first significant snow of the winter arrived in the isles on Friday, a week later than the mainland, and the icy conditions led to some minor traffic accidents. Two people were taken to hospital on Friday morning when the bus they were travelling in went off the road.

The bus, with 10 people on board, was going from Walls to Lerwick when it slid into a ditch at Weisdale just after 10.30am. Police and three fire appliances from Lerwick, Brae and Bixter went to the scene, but were not required.

The two people hurt in the incident were taken to Gilbert Bain Hospital in Lerwick for treatment to suspected minor injuries. They were released from hospital after being seen in the hospital’s accident and emergency department, and did not need to be admitted.

The remaining eight people were taken on to Lerwick shortly after the collison.

Police described the one vehicle collision as “minor”, and said there have been a number of other traffic “bumps” due to motorists losing control of their vehicles in the snow. In some cases the vehicles have been extensively damaged but there have been no serious injuries.

An ambulance with a patient on board got stuck in the snow when travelling between Scalloway and Lerwick at around 8pm on Friday. A gritter had to be summoned to give assistance before the ambulance could continue its journey.

The national salt shortage is also affecting Shetland. Head of roads Ian Halcrow said: “Unfortunately with the national shortage of salt for gritting roads, we are unable to get those stocks replenished at this time. Salt has been ordered, but with the situation nationally we are unsure when we will be able to get supplies delivered to us.

“We are therefore going to have to take measures to conserve the salt that we have remaining. From [Tuesday], we will only be using salt on Priority 1 routes which essentially is main roads carrying heavy traffic.

“All other roads will be treated with grit only, without salt. We will also only be able to use salt on footpaths in Lerwick and Scalloway used by the highest number of pedestrians. Drivers are urged to travel with care as many roads will be more slippery than normal.”

Fair Isle weatherman Dave Wheeler forecasts another hard frost on Monday night with snow showers becoming more frequent in the next few days and a freshening northerly wind.